I've both of my APN .p8 files, but now I can't create more as the limit of this key is 2. Is it possible to revoke the current key and then create another one? I don't want to take the risk of trying it out before any confirmation.
I've lost my APN .p8 file
If you lost your .p8 files, our recommendation would be to revoke them, as they are no longer any use to you, and you wouldn't want someone else who has them to be able to use them.
After revoking you should be able to create a new key.